The application of camshaft position sensors in internal combustion engine control is known generally in the art of engine control. For instance, such sensors may provide engine absolute position information which may be used to synchronize relative position inputs to the control, such as from a crankshaft position sensor. The camshaft position sensor is typically a dedicated sensor, such as a conventional variable reluctance sensor disposed in proximity to the camshaft to sense passage of an appendage placed on the camshaft, and to communicate the passage to a controller for use in synchronizing a relative engine position input. Significant expense is associated with this approach to sensing camshaft position including the cost of the variable reluctance sensor and the associated packaging and wiring, and the additional machining on the camshaft.
In a direct ignition system (DIS) for spark plug ignition in an internal combustion engine, pairs of spark plugs are coupled to a single supply. The supply may be a conventional step-up transformer, the timing of the charge and discharge of which are controlled by a spark controller. The pair of spark plugs may be coupled in series across the secondary winding of the transformer in reverse electrical polarity, wherein the anodes of the pair are grounded. The transformer provides energizing voltage to the pair of spark plugs whenever either of the two must be fired for desired engine control. DIS provides a cost advantage over electronic ignition systems having one dedicated coil per spark plug.
Accordingly, it would be beneficial to supplant the camshaft position sensor with a low cost alternative thereto that is suitable for application with DIS.